The present invention concerns a diverter valve for an extruder, especially a twin-screw extruder.
Typically, diverter valves are used to simplify the starting process for extruders, especially twin-screw extruders, and in particular for extruders used for granulation. Only by using a diverter value can the point time of the exit of melts from the cutting plate and, therewith, the correct time for turning on the granulator and transport water, be precisely ascertained.
Diverter valves, which are commercially available, must nonetheless be completely, including the subsequent granulator (for example, an underwater granulator), dismantled and removed before the screw can be pulled out of the extruder housing.
Reference is made generally to German patent document DE 101 51 434 regarding an underwater granulator with a pivoted water tube conduit, in which the advantages of an underwater granulator, which can be folded away in a simple manner, are described.
Generally, in the case of an underwater granulator, a rotating blade tool of a cutting device cuts up a large number of strands of melts, which are pressed through a die plate equipped with bores, into short pieces. This leads to pellets. The underwater granulator is coupled to the extruder during operation, preferably while interposing the aforementioned diverter valve.
The swiveling underwater granulator in accordance with DE 101 51 434 already clears the space in front of the extruder in its folded away state. When using a cutting plate with quick couplings, it can be dismounted in the shortest time possible to pull the extruder screw out of the extruder housing when the diverter valve is dispensed with.
The object of the present invention is to provide a diverter valve that is designed for use in connection with an extruder, especially a twin-screw extruder, and guarantees rapid dismounting of the extruder screws (worm gears).
This objective is accomplished by providing a diverter valve for an extruder, especially a twin-screw extruder, including a valve housing with a first flow passage, which can be fastened indirectly or directly on an extruder cylinder, whereby the valve housing can be arranged on the extruder cylinder with a first flow passage that can be arranged in alignment with the screw area, and the cross section of the first flow passage is constructed large enough in order to pass extruder screws arranged in the extruder through the flow passage, as well as a valve bolt arranged with its axis basically perpendicular to the direction of flow of a liquid or a melt in the valve housing, with at least one further through flow passage which can be arranged in a position that is aligned with the first flow passage of the valve housing and whose cross section is likewise constructed large enough to pass the extruder screws arranged in the extruder through this second flow passage, whereby the valve bolt is arranged adjustably in the valve housing.
Accordingly, a valve housing with a first flow passage is connected to the extruder. The valve housing accommodates a valve bolt, the axis of which is arranged basically perpendicular to the direction of flow of the fluid or the melt. The valve bolt has a second flow passage, which can be matched with the first flow passage of the valve housing to produce a general opening through the diverter valve. The two flow passages are constructed in terms of their dimension such that the extruder screws arranged in the extruder can be drawn through the overall flow passage. In this way, a diverter valve does not represent any hindrance for dismounting or mounting the extruder screws. If a twin-screw extruder is used, the flow passages can preferably be constructed in the form of spectacle-type (eyeglass shaped) bore holes.
A basically groove-like recess is arranged on the outer periphery of the valve bolt in addition to the second flow passage in the valve bolt, axially at the same height, but radially offset. With this groove-like recess, a melt flow that is introduced through an inlet channel into the diverter valve can be guided in one position of the valve bolt into a starting channel around and out of the diverter valve. In another position of the bolt, the second flow passage connects the inlet and outlet channel of the first flow passage of the valve housing. Switching can take place by rotating the valve bolt about its axis of rotation. Alternatively, the switch can also take place by sliding the valve bolt.
In order to keep the diameter of the bolt as small as possible, the latter is arranged in the valve housing such that the central axes of the extruder screw or the extruder screws intersect about the central axis of the bolt.
Of course, the valve bolt can be manually activated. Alternatively, activation though a drive, for example a hydraulic or electric drive, is possible. The diverter valve can be designed as a separate part. Nonetheless, an embodiment in which it is incorporated in an extruder is also advantageous. For this, the bore hole for the seat of the pivot bolt can be inserted in the extruder cylinder.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.